SG-121-H unlimited hydro build.

[CatBoi]

Hello, its been quite awhile...

building a 1/8 scale F.E. unlimited hull. RCboat Company's SG121-H.

I am considering power options.. I have been out of it for a few years so any suggestions are welcome!

I was thinking- a neu 2215? 8-10 cells? 200 amp esc or more?

?

I think this was the last boat I built...

[RayR]

Welcome back Sandy,

Most of the 1/8th scale folks are running a Neu 1527 1.5Y on 10S or a 1530 1Y on 8 or 9S. A 200+ amp HV speedo is the norm. If you don't care about the competition scene, the motor choices are almost limitless. Which livery will you be modeling? I am certain it will look as fantastic as all of your previous builds.

If you need any further assistance, feel free to give me a shout.

All the best,

Ray

[CatBoi]

ok, thanks for the info...so to refresh my neu motor memory, 1y produces more rpm than 1.5y? I kinda forgot what that meant...

here is the ambitious paint scheme-

[Agitator]

The 1530 1Y is 1100 rpm per kv=on 8s=32500 rpm with a fairly high amp draw. 1527 1.5Y is 850kv-on 10s=31450 rpm with less amp draw. cooler and more efficient. Most of us use a 1/4" drive cable with a 3/16" step down on the prop.
Mike McKnight@Thunderboat Graphics should have those graphics available in a few months.

[CatBoi]

ok, thank you all for the infos! another question is what is the average size packs they run, 4000, 5000?

[Agitator]

6000mah, if you can get them in. These are Giant Power 6000mah 5s packs in my ML Boatworks '89 Winston Lobster. With Steve's hull, you have to build a watertight box for everything-batteries-motor-scu-Rx, etc. Batteries should go in the bow as far forward as possible. 014.jpg

[CatBoi]

does anyone have a photo of thier set-up they would like to share? motor, esc, etc...

[CatBoi]

Power plant, Neu 1527 . Hull should be here in a week or so..

[nichismo]

Hey Catboi, I actually have the exact same hull from Steve and have been on a very long project with it for a very long time now. Im sure I can at the very least provide you with some decent insight on anything you need to know regarding an electric powerplant in this hull.

For starters, I must say that im actually building the boat to replicate the U-88/U-37 drop sponson hull that Billy Schumacher owns, so this hull as pulled from Steves molds is far from correct in this perspective, and in addition to a few other specific characteristics of the hull that I wasnt keen on (regardless of the full size boat I chose) led me to do a very extensive list of modifcations to make it right.

Also, in my opinion, Steve implemented a somewhat outdated design philosophy for this style of hull when it comes to the bottom of the hull, and even worse, the hull is EXTREMELY HEAVY. When it was shipped to me, the package was over 15lbs.... I also own a Phil Thomas T5 and I dont remember what that package weighed when I received it, but the bare hull was about 6lbs.... So this led to even more substantial modifications on my part, but in the end, im still satisfied at this point. On a positive note, Steve uses excellent materials and does a good job cleaning up the hull overall before he sends it. The wing mounts are fantastic, quality flotation is already installed in virtually every spot possible, and aside from the underside of the hull as mentioned, the overall aesthetics and scale accuracy of the boat is superb, specifically the front curves and shapes of the boat (im a fickler for sponson shape and cockpit shape, and he really nailed these parts).

I have a ton of pictures if you need any, starting from the moment I began opening the packaging until now. Heres a picture of the most recent mock-up I did with all the components, except the ESC which ill be placing in a compartment I made on the starboard side of the boat. I should note that in this picture, I had already opened up the radio box area by removing the enclosing wall to make the tub open all the way through the length of the hull...... and then i proceedingly removed virtually all of the tub and floor between the cockpit and rear strut area.....The floor section that runs from the nitro engine mounted blocks he has epoxied into the hull towards the back was 1.25 pounds alone.... Since then ive closed the tub back up with plywood.

Let me know if you have any other questions, im happy to help if I can. BTW, that motor mount configuration pictured is excellent, you need a narrow setup similar to that for these boats. and as stated already, its absolutely critical that you get the batteries as far foward as possible. Thankfully with this particular hull, the radio box is already big enough to fit a 10s, 5500mah setup as molded.

[CatBoi]

Ok,

We start with the bare hull as supplied from RC Boat Company... Most of the parts I got from OSE or other sources.


We Start by dry fitting everything, starting with the batteries. There is enough room to move the packs back and forth about 2 inches so fine tuning the balance should easier this way. I choose to mount the motor mid-ship as to keep the model balanced and driveshaft short. I can always add a few ounces of lead to the nose if needed, but taking weight off would be much harder... this also allows room for the esc to be mid mounted between batteries and motor keeping the power leads as short as possible....

[CatBoi]

Next, I re-made the motor mount rails from scrap 3mm carbon fiber so I could bond them to the floor easier than the alu plates...

[CatBoi]

Now you can see the layout a bit better, only a slight notch was needed to produce a good fit for the motor, carbon was added to the floor during the layup process.

I had to close up the battery box area so scrap fiberglass was used to make the filler panels.

[CatBoi]

The stock brass cooling tubes we replaced with larger stainless steel lines and their position adjusted for F.E. .

A small carbon back up plate was used for the exits.

[CatBoi]

Let's move onto some part fitment... the turbine tray was enhanced with carbon fiber and west system epoxy to stiffen it.

[CatBoi]

I decided to cut the cockpit free and make separate sections of the cowl using carbon bulkheads made from scraps.
The cockpit is attached separately from the main cowl as per the full size boat. A lot of patience and care used here , more on the cowl later....